Conventionally, when a refrigerant leak occurs in an air-conditioning apparatus having an accumulator, and when there is an excessive liquid refrigerant in the accumulator, a liquid level of the excessive liquid refrigerant merely lowers and temperature and pressure of a refrigeration cycle do not change. For this reason, even when leakage of the refrigerant occurs in the air-conditioning apparatus having the accumulator, it cannot be detected.
Accordingly, a variety of air-conditioning apparatuses which are configured so as to detect shortage of a refrigerant has been proposed. As one of these apparatuses, an air-conditioning apparatus is disclosed in which a sight glass is provided in an accumulator and a shortage of a refrigerant is detected by a method in which operating conditions coincide with reference conditions by performing a special operation (for example, refer to Patent Literature 1).
Further, an air-conditioning apparatus is disclosed which has an accumulator provided with a liquid level detection circuit such that a shortage of a refrigerant is detected while the state of the circuit is being measured (for example, refer to Patent Literature 2). Moreover, an air-conditioning apparatus is disclosed in which a special operation is performed and a measurement value concerning an amount of a liquid phase portion of a refrigerant in a high pressure side heat exchanger (a value of liquid phase temperature efficiency εL (SC/dTc) calculated from temperature information), and a theoretical value (a value of a liquid phase temperature efficiency εL (1-EXP(-NTUR) obtained from the number of transfer units NTUR on a refrigerant side) are calculated and compared to each other, whereby precise diagnosis of normality or abnormality is conducted (for example, refer to Patent Literature 3).
In addition, an air-conditioning apparatus is disclosed in which by performing a special operation of bringing the interior of an accumulator into a gas state, a refrigerant filled state is determined on the basis of a result of comparison between a predetermined value and a value obtained by calculation of a condenser liquid phase area ratio which is a value concerning an amount of refrigerant in a liquid phase portion in a high pressure side heat exchanger (for example, refer to Patent Literature 4).